Get 10 coins. Once you do that, go to the Tic Tac Trump game in the casino. Bet 6 coins, don't double, then lose. Even though you have 4 coins left, the game will allow you to bet 6 coins. Do this and lose, you will now have -2 coins. Quit the mini-game, but play again, bet any amount, and win. You should now have 9,999,999 coins.